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Comparison of Organ and Effective Dose Estimates for CT Exams Obtained From Two Commercially Available Radiation Dose Monitoring Software (RDMS) Systems

M Bostani*, C Cagnon, T Oshiro, M McNitt-Gray, University of California, Los Angeles, Los Angeles, CA


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Radiation Dose Monitoring Software (RDMS) systems are being used to assist in reporting CT doses required by accreditation standards. These systems also provide organ and effective dose estimates. The purpose of this work was to compare the organ and effective dose estimates for CT exams obtained from two RDMS systems.
For a total of 48 adult and pediatric CT exams (24 males, 24 females) of various sizes and from three different exam types (16 routine head, 16 chest and 16 abdomen/pelvis), identical image data and dose reports were provided to two commercially available RDMS systems. For each patient, water equivalent diameter (Dw), organ doses and effective dose (ED) estimates were extracted from each RDMS system and percent differences were calculated. For each exam type, maximum, mean and standard deviation of percent differences between estimates were reported for ED, organ dose and Dw.
For head CT exams, the maximum percent differences were 74% for ED and 41% for brain dose; it should be noted that only one system calculated Dw for head exams. For chest exams, the maximum percent differences were 39% for ED, 27% for lung dose and 63% for Dw. For abdomen/pelvis exams, the maximum percent differences were 34% for ED, 11% for colon dose and 62% for Dw.

When provided the same input data, two RDMS produced substantially different values in effective dose, organ dose and water equivalent diameter values. While differences in calculated values were not entirely unexpected, the magnitude was surprising. We consider differences in reported ED to be too large to reliably communicate dose and risk to patients and clinicians. Further work needs to be conducted to standardize and validate dose calculations across the industry before they can be credibly used.


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